Air/fuel mixing system controlled by temperature activated mechanism for internal combustion engines

ABSTRACT

An improvement in air/fuel mixing systems controlled by temperature activated mechanism for internal combustion engines, embodied in air/fuel mixing means which permit the carburetor to be initially adjusted for efficient economical performance to maintain a variable nearly perfect air/fuel mixture for combustion under a wide range of operating conditions by varying the pressure in the float bowl of the carburetor, achieved by connecting a vacuum source to the carburetor float bowl by a vacuum conduit whereby the difference between the pressure in the fuel bowl and the pressure in the Venturi throat of the carburetor is reduced. The temperature activated mechanism is incorporated into the mixing system and provides an automatic over-temperature safety cutout device which is a thermal vacuum valve that simultaneously disables the main air/fuel mixing system and enables the distributor advance upon sensing an overtemperature condition.

United States Patent [19] Berry et al.

[451 Feb.5, 1974 AIR/ FUEL MIXING SYSTEM CONTROLLED BY TEMPERATURE ACTIVATED MECHANISM FOR INTERNAL COMBUSTION ENGINES [75] Inventors: James M. Berry, Boulder; William C. Womack, Lafayette, both of C010.

[73] Assignee: Colspan Environmental Systems,

Inc., Boulder, C010.

22 Filed: Apr. 10,1973

211 App]. No.: 349,686

[52] U.S. Cl. 123/117 A, 123/97 B, 123/119 R, 123/136, 261/39 R, 261/72 R, 26l/DIG. 67

[51] Int. Cl. F02m 7/00, F02p 5/00 [58] Field of Search. 123/97 B, 117 A, 119 R, 136; 261/DIG. 67, 39 R, 72 R [56] References Cited UNITED STATES PATENTS 1,041,662 10/1912 Noyes.. 123/136 3,080,858 3/1963 Kane 123/97 B 3,301,242 l/l967 Candelise.... 123/117 A 3,400,698 10/1968 Kelly 123/117 A 3,677,241 7/1972 Gele et al 123/97 B 3,742,924 7/1973 Bachle 123/119 R Primary Examiner-Al Lawrence Smith Assistant Examiner-Tony Argenbright Attorney, Agent, or Firm-Bertha L. MacGregor [57] TRACT An improvement in air/fuel mixing systems controlled by temperature activated mechanism for internal combustion engines, embodied in air/fuel mixing means which permit the carburetor to be initially adjusted for efficient economical performance to maintain a variable nearly perfect air/fuel mixture for combustion under a wide range of operating conditions by varying the pressure in the float bowl of the carburetor, achieved by connecting a vacuum source to the carburetor float bowl by a vacuum conduit whereby the difference between the pressure in the fuel bowl and the.

pressure in the Venturi throat of the carburetor is reduced. The temperature activated mechanism is incorporated into the mixing system and provides an automatic over-temperature safety cutout device which is a thermal vacuum valve that simultaneously disables the main air/fuel mixing system and enables the distributor advance upon sensing an over-temperature condition.

7 Claims, 2 Drawing Figures AIR/FUEL MIXING SYSTEM CONTROLLED BY TEMPERATURE ACTIVATED MECHANISM FOR INTERNAL COMBUSTION ENGINES This invention relates to an air/fuel mixing system controlled by temperature activated mechanism for internal combustion engines. The temperature activated mechanism is embodied in air/fuel mixing means which permit the carburetor to be initially adjusted for efficient economical performance to maintain a variable nearly perfect air/fuel mixture for combustion under a wide range of operating conditions by varying the pressure in the float bowl of the carburetor. This is achieved by connecting a vacuum source to the carburetor float bowl by a valved conduit. The connection of the vacuum source, which may be the intake manifold of the engine or other source, to the carburetor fuel bowl, results in reducing the difference between the pressure in the fuel bowl and the pressure in the Venturi throat of the carburetor, whereby flow of fuel is inhibited under most operating conditions, resulting in maintenance of relatively uniform air/fuel mixture fed to the intake manifold of the engine. This air/fuel mixing system herein shown and described will be referred to herein as the lautomix system.

The temperature activated mechanism of this invention is incorporated into the automix system to provide automatic over-temperature safety cutout and to prevent overheating of the engine. The automatic overtemperature safety cutout device is a thermal vacuum valve that simultaneously disables the main automix system and enables the distributor vacuum advance upon sensing an over-temperature condition.

The thermal vacuum valve consists of two valve elements, one a normally closed valve and the other a normally open valve, which are mechanically controlled from a temperature sensing element that expands mechanically with temperature until a point is reached at which an integral snap action mechanism is activated which simultaneously operates both valve elements.

An object of the invention is to provide the two valve elements, snap action mechanism and temperature sensing/expansion element packaged in an integral housing suitable for installation in the upper radiator hose of a vehicle where the sensing expansion element senses the temperature of the cooling water circulating through the engine. The normally open valve is operatively connected in the main vacuum conduit of the automix system, and the normally closed valve is operatively connected in the vacuum advance line of the auto distributor.

-A further object of the invention is to provide a proprietary mixing valve unit installed in the main vacuum conduit of the automix system for controlling the air/fuel mixture of the engine (a) by applying variable partial vacuum to the float bowl chamber of the carburetor and hence leaning the mixture as a function of engine speed, load, and altitude; and (b) by providing additional dilution of the air/fuel mixture through a controlled orifice/vent control valve assembly. The mixing valve unit consists of three functional elements packaged into an integral housing, namely: a flow limiting orifice, mixing chamber and vent control valve. The aforesaid mixing valve unit is disabled by the temperation of the engine exists.

Another object of the invention is to provide a Venturi feedback line communicating at one end with the Venturi throat of the carburetor and connected at its other end to the main vacuum conduit that leads from the engine intake manifold (or other vacuum source) to the top of the carburetor float bowl for the purpose of reducing the difference between the pressure in the fuel bowl and the pressure in the Venturi throat of the carburetor, whereby flow of fuel is inhibited under most operating conditions and relatively uniform air/fuel mixture is maintained. More particularly, the feedback system functions to maintain the desired air/fuel mixture following certain closed-throttle conditions described herein.

The temperature activated mechanism of this invention may be incorporated into the automix system provided with the aforementioned feedback line or without the feedback line, as will be explained herein by reference to the drawings.

In the drawings:

FIG. 1 is a diagrammatic view, partly in section, showing a carburetor for an internal combustion engine and part of an engine intake manifold embodying the automix system, and provided with the temperature activated mechanism of this invention.

FIG. 2 is a view similar to FIG. 1, but showing the temperature activated mechanism of this invention embodied in a modified form in which the automix system includes the carburetor Venturi throat feedback line.

In the embodiment of the invention shown in the drawings, the carburetor 10 of the automix system comprises a Venturi tubular body 11, air intake throat 12, fuel nozzle 13 with orifice 14, within the body 11, and an air/fuel mixture outlet 15 leading to the engine intake manifold 16. the carburetor fuel chamber 17 is provided with a float 18 and float valve 19 fed by fuel line 20 communicating with a fuel supply and pump (not shown). In conventional carburetors, the housing of the fuel chamber 17 is provided with an atmosphere vent in its upper wall 21; said vent is eliminated for purposes of this invention. A main vacuum conduit 25 is connected at 26 to the housing wall 21 in communication with the chamber 17. The connection 26 may be made in the wall 21 in the place where the atmosphere vent would be located in a conventional carburetor float chamber housing. The vacuum conduit 25 communicates with the engine intake manifold 16 through coupling 27.

The vacuum existing in the engine intake manifold is created by the normal operation of the pistons in the cylinders of the engine (not shown). The conduit 25 communicating with the engine intake manifold and with the top of the fuel chamber results in placing a vacuum source at the top of the fuel in the chamber. In other words, it reduces the pressure in the float chamber. The fuel no longer has atmospheric pressure acting on it. The pressure in the float chamber is now lower than atmospheric pressure. By controlling the pressure in the float chamber, the amount of fuel flowing into the air stream can be controlled. This is because the fuel flow is controlled by the difference in pressure in the float chamber and the pressure in the Venturi throat.

The vacuum source can come from the engine itself or it may be an external source such as a vacuum pump. When the vacuum source is the engine intake manifold, the pressure can be tapped from the positive crank case ventral valve line or from the vacuum spark advance line or directly from the intake manifold.

The parts heretofore described comprise the automix system to which the temperature activated mechanism of our invention is applied. Said mechanism comprises a normally open valve element 30, a normally closed valve element 31, mechanically controlled from a temperature sensing element 32, mounted in the top radiator hose 33. The element 32 mechanically expands in response to increased temperature until a point is reached at which an integral snap action mechanism (not shown) is activated which simultaneously operates both valve elements 30, 31, thereby closing valve 30 and opening valve 31. The elements 30, 31, 32 are packaged in an integral housing, installed in the upper radiator hose 33 of a vehicle for sensing the temperature of the cooling water circulating through the engine. The mechanism is designed to operate at a pre-set temperature ranging from 205 to 215 F. (engine overtemperature condition). Upon operation of the valves 30, 31, the automix pneumatic control system is disabled and the normal distributor vacuum advance line 35 is enabled. Both functions tend to lower engine heat output and reduce the cooling water temperature. When the water temperature drops below the operating temperature range of 205 to 215 F., the system returns to its normal operating state, i.e., automix operating and distributor vacuum advance disabled.

A proprietary mixing valve unit 40 is incorporated into the main vacuum conduit 25 of the automix system that controls the air/fuel mixture of the engine (a) by applying variable partial vacuum to the float bowl chamber 17 of the carburetor and hence leaning the mixture as a function of engine speed, load and altitude, and (b) by providing additional dilution of the air/fuel mixture through a controlled orifice/vent control valve assembly.

The mixing valve unit 40 comprises three functional elements packaged into an integral housing, including the flow limiting orifice 41, mixing chamber 42 and vent control valve 43. The flow limiting orifice 41 is a small pneumatic orifice designed to maintain the air flow through the mixing valve unit at a relatively small and constant value. The critical flow through the orifice is substantially below the normal operating region; hence a non-linear differential pressure drop across the orifice is derived. This non-linearity is critical to the proper functioning of the system. A typical ratio of input to output pressure is approximately 26 to 1. This orifice 41 also limits the dilution of the air/fuel mixture going into the engine.

The mixing chamber 42 of the unit 40 is a small cylindrical chamber connecting the mixing valve unit input (low vacuum side) and the vent control valve 43 with the flow limiting orifice 41. The purpose of this chamber is to properly mix the air flows from both the input (carburetor float bowl chamber 17) and the vent control valve 43 such that an equilibrium pressure (partial vacuum) is maintained within the float bowl chamber 17. This pressure varies as a function of engine speed, load and altitude conditions.

The vent control valve or air bleed valve 43 provides an adjustable controlled air leak into the system thus controlling both the differential pressure applied to the carburetor float bowl chamber 17 as well as the dynamic response of the system. This valve 43 permits adaptability of the automix system to a wide variety of engines and automatically compensates for different carburetor design, functional parameters, and operating conditions.

Referring to the modification shown in H6. 2, a feedback line 50 is installed in the automix system by inserting one end 51 of the line into the open top 12 of the Venturi throat 15 of the carburetor and connecting the other end 52 to the vent control valve 43. The feedback line is particularly designed to function for the purpose of maintaining desired air-fuel mixture following certain closed-throttle performance of the vehicle of which it is a part.

While testing the automix system comprising the parts 10-27 described herein, installed in the internal combustion engine of an automobile, it was noted that after a long downhill coasting run, with throttle closed, and a start-up on the next hill, with accelerator depressed and throttle open, a hesitation in power pickup occurred. The hesitation was a slowing for approximately 5-10 seconds before the engine reacted to the depression of the accelerator and opening of the throttle after the long coasting period. It was observed that during the downhill coasting, with throttle closed or nearly closed, the vacuum was very high in the carburetor float bowl which resulted in very little gasoline getting into the engine intake manifold. Therefore the feedback arrangement described herein was provided to eliminate the lag in power pick-up observed after a substantially fuel-free downhill coasting run, thus providing means whereby the relatively uniform air/fuel mixture fed to the intake of the engine is maintained under all operating conditions. The automix system without the feedback means may be provided with the temperature activated mechanism of this invention, as shown in FIG. 1, or the automix system together with the feedback means may be provided with the temperature activated mechanism as shown in FIG. 2.

We claim:

1. An air/fuel mixing system controlled by temperature activated mechanism for internal combustion engines comprising a a carburetor and a main vacuum conduit connecting a vacuum source to the carburetor fuel chamber for varying the pressure in the chamber and thereby automatically varying the flow of fuel from the chamber to the intake manifold of an engine,

b a distributor advance line connected to the vacuum source, and

c an automatic over-temperature safety cutout device mounted to sense the temperature of cooling water in the top radiator hose of an engine, and simultaneously disables the air/fuel mixing system and enables the distributor advance upon sensing an overtemperature condition.

2. The system defined by claim 1, in which the safety cutout device comprises a normally open valve in the main vacuum conduit, a normally closed valve in the distributor advance line, and a temperature sensing unit connected to said valves and automatically opening said normally closed valve and automatically closing said normally open valve when an over-temperature condition is sensed.

3. The system defined by claim 1, which includes a mixing valve unit connected into the main vacuum conduit of the system, that controls the air/fuel mixture of the engine by applying variable partial vacuum to the carburetor float bowl under varying conditions of engine speed, load and altitude, and by providing additional dilution of the air/fuel mixture through a controlled orifice vent control valve assembly in the main vacuum conduit.

4. The system defined by claim 3, in which said orifice vent control valve assembly comprises a mixing chamber in the main vacuum conduit, a flow limiting orifice and a vent control valve, the critical flow through the orifice being substantially below the normal operational flow.

5. The system defined by claim 2, which includes a mixing valve unit connected into the main vacuum conduit of the system, that controls the air/fuel mixture of the engine by applying variable partial vacuum to the carburetor float bowl under varying conditions of engine speed, load and altitude, and by providing additional dilution of the air/fuel mixture through a controlled orifice vent control valve assembly in the main vacuum conduit.

6. An air/fuel mixing system controlled by temperature activated mechanism for internal combustion engines, comprising a a carburetor including a fuel chamber, a body having an air intake and a Venturi throat, an orificed I fuel nozzle in the throat and means connecting the carburetor body to the intake manifold of an engine,

b a vacuum source,

c a main vacuum conduit connecting the vacuum source to the carburetor fuel chamber for varying the pressure in the chamber and thereby automatically varying the flow of fuel from the chamber to the orificed nozzle in the throat,

d a normally open valve in said main vacuum conduit,

e a vacuum distributor advance line connected to the vacuum source and having a normally closed valve in said vacuum advance line, and

f a temperature sensing and control unit mounted to sense the temperature of cooling water in the top radiator hose of the engine, and connected to said normally open valve in said main vacuum conduit and to said normally closed valve in said vacuum advance line, whereby sensing of an overtemperature condition automatically disables the main air/fuel mixing system and enables the distributor advance line.

7. The system defined by claim 6, which includes a feedback line having one end inserted into the open top of the venturi throat of the carburetor and the other end connected to the main vacuum conduit. 

1. An air/fuel mixing system controlled by temperature activated mechanism for internal combustion engines comprising a a carburetor and a main vacuum conduit connecting a vacuum source to the carburetor fuel chamber for varying the pressure in the chamber and thereby automatically varying the flow of fuel from the chamber to the intake manifold of an engine, b a distributor advance line connected to the vacuum source, and c an automatic over-temperature safety cutout device mounted to sense the temperature of cooling water in the top radiator hose of an engine, and simultaneously disables the air/fuel mixing system and enables the distributor advance upon sensing an over-temperature condition.
 2. The system defined by claim 1, in which the safety cutout device comprises a normally open valve in the main vacuum conduit, a normally closed valve in the distributor advance line, and a temperature sensing unit connected to said valves and automatically opening said normally closed valve and automatically closing said normally open valve when an over-temperature condition is sensed.
 3. The system defined by claim 1, which includes a mixing valve unit connected into the main vacuum conduit of the system, that controls the air/fuel mixture of the engine by applying variable partial vacuum to the carburetor float bowl under varying conditions of engine speed, load and altitude, and by providing additional dilution of the air/fuel mixture through a controlled orifice vent control valve assembly in the main vacuum conduit.
 4. The system defined by claim 3, in which said orifice vent control valve assembly comprises a mixing chamber in the main vacuum conduit, a flow limiting orifice and a vent control valve, the critical flow through the orifice being substantially below the normal operational flow.
 5. The system defined by claim 2, which includes a mixing valve unit connected into the main vacuum conduit of the system, that controls the air/fuel mixture of the engine by applying variable partial vacuum to the carburetor float bowl under varying conditions of engine speed, load and altitude, And by providing additional dilution of the air/fuel mixture through a controlled orifice vent control valve assembly in the main vacuum conduit.
 6. An air/fuel mixing system controlled by temperature activated mechanism for internal combustion engines, comprising a a carburetor including a fuel chamber, a body having an air intake and a Venturi throat, an orificed fuel nozzle in the throat and means connecting the carburetor body to the intake manifold of an engine, b a vacuum source, c a main vacuum conduit connecting the vacuum source to the carburetor fuel chamber for varying the pressure in the chamber and thereby automatically varying the flow of fuel from the chamber to the orificed nozzle in the throat, d a normally open valve in said main vacuum conduit, e a vacuum distributor advance line connected to the vacuum source and having a normally closed valve in said vacuum advance line, and f a temperature sensing and control unit mounted to sense the temperature of cooling water in the top radiator hose of the engine, and connected to said normally open valve in said main vacuum conduit and to said normally closed valve in said vacuum advance line, whereby sensing of an over-temperature condition automatically disables the main air/fuel mixing system and enables the distributor advance line.
 7. The system defined by claim 6, which includes a feedback line having one end inserted into the open top of the venturi throat of the carburetor and the other end connected to the main vacuum conduit. 